Nobody has ever yet been able to devise a universal scale by which thoughts may be measured, nor any acid test to distinguish gold from dross in art and literature. So each person has to devise a scale of his own and do his measuring for himself; he has to apply to the things he sees and reads the acid test of his own intellect. And however imperfect this measuring and testing may be, it is the only sort which has any value for that particular person. In other words, unless you yourself find a poem or a painting great, it isn't great for you, however critics may extol it. So all the books about art and literature and music are of value only as they improve the scale and perfect the acid test of the individual, so that the former measures more and more correctly, and the latter bites more and more surely through the glittering veneer which seeks to disguise the dross beneath. It follows from all this that, since there are nearly as many scales as there are individuals, very few of them will agree exactly. Time, however, has a wonderful way of testing thoughts, of preserving those that are worthy, and of discarding those that are unworthy. Just how this is done nobody has ever been able to explain; but the fact remains that, somehow, a really great poem or painting or statue or theory lives on from age to age, long after the other products of its time have been forgotten. And if it is really great, the older it grows, the greater it seems. Shakespeare, to his contemporaries, was merely an actor and playwright like any one of a score of others; but, with the passing of years, he has become the most wonderful figure in the world's literature. Rembrandt could scarcely make a living with his brush, industriously as he used it, and passed his days in misery, haunted by his creditors and neglected by the public; to-day we recognize in him one of the greatest artists who ever lived. Such instances are common enough, for genius often goes unrecognized until its possessor is dead; just as many men are hailed as geniuses by their contemporaries, and promptly forgotten by the succeeding generation. The touchstone of time infallibly separates the false and the true. Unfortunately, to American literature and art no such test can be applied, for they are less than a century old--scarcely out of swaddling clothes. The greater portion of the product of our early years has long since been forgotten; but whether any of that which remains is really immortal will take another century or two to determine. So the only tests we can apply at present are those of taste and judgment, and these are anything but infallible.